Risk factors for ventilator associated pneumonia due to carbapenemase-producing Klebsiella pneumoniae in mechanically ventilated patients with tracheal and rectal colonization

BACKGROUND: The aim of this study was to identify the risk factors for ventilator associated pneumonia (VAP) due to Klebsiella pneumoniae carbapenemase-producing K (KPC-Kp) development in ICU patients with documented rectal and tracheal colonization. METHODS:. We performed a retrospective, matched case-control study in a medical-surgical ICU (January 2011-December 2013) comparing 30 patients who developed KPC-Kp VAP during the ICU stay to 60 colonized patients not developing KPC-Kp VAP. Analysed risk factors included: age, sex, SAPS II and SOFA scores, comorbidities, type and length of antibiotic therapy, previous non KPC-Kp infections, time between admission to rectal and tracheal colonization. RESULTS: Several risk factors were more frequent among patients who developed KPC-Kp pneumonia versus matched colonized controls: previous infection not related to KPC-Kp (P<0.001), duration of previous antibiotic therapy before (P<0.001) and after (P=0.002) KPC-Kp colonization. Amoxicillin/clavulanic acid prophylaxis was administered in 17% of VAP patients versus 73% of patients not developing VAP (P<0.001). Multivariate conditional logistic regression analysis identified several significant independent risk factors favoring KPC-Kp VAP in patients colonized at multiple sites: previous non KPC-Kp infections (OR: 2.046), duration of previous antibiotic therapy before (OR: 1.309) and after (OR: 1.122) KPC-Kp colonization; antibiotic therapy with amoxicillin/clavulanic acid prophylaxis (<48 hours) was associated with reduced risk of KPC-Kp VAP (OR: 0.987). CONCLUSIONS: In rectal and tracheal KPC-Kp colonized patients, prolonged antibiotic therapy administered for non KPC-Kp infection predisposes patients to subsequent KPC-Kp VAP. Short prophylaxis of early pneumonia with amoxicillin/clavulanic acid, reducing the need for subsequent antibiotic use, may be associated with reduced risk for KPC-Kp VAP.